Label-free detection of microRNA by polymerization and isomerization cyclic amplification coupled with G/Hemin DNAzyme

A label-free detection technique for microRNA (miRNA) was developed based on target replacement cycling, polymerization and isomerization cyclic amplification (PICA), and G/Hemin DNAzyme signal output. The designed hairpin probe undergoes cyclic alternation of polymerization and isomerization catalyzed by Bst DNA polymerase, enabling target replacement cycling and continuous self-extension of single-stranded DNA (ssDNA) strands. This process generates abundant G-quadruplex sequences that bind to Hemin, achieving label-free detection of miRNA through catalytic reactions. Its key advantages include a specific primer self-extension mechanism that avoids spurious amplification, one step isothermal design simplifies workflow and enhances system robustness, adapting to diverse detection scenarios, and label-free detection strategy that substantially reduces cost. Therefore, it is poised to become a reliable tool for clinical miRNA analysis, offering potential guidance for the early diagnosis, treatment, and prognosis of tumor biomarkers.